Sounds like it needs fuel system clean up as suggested. Do you run ethanol in it? SGE's that set over winter (takes 3 or 4 years to build up some times) all experience this sooner or later. To prevent this don't let them set for months at time and routinely treat the gas with fuel treatment especially if all you can get is ethanol gas. The rough idle IMO from small passages gummed up or maybe the main jet that Bayless talks about all the time. Hopefully fuel treatment will dissolve the gummed up passages and you won't have to disassemble the carb. to clean them out or at least take the fuel bowl off and spray what passages you can see from the top and bottom. If you do take the fuel bowl off just make sure you get the 0-ring seated correctly or it will dribble gas out the sides of the fuel bowl and be fire hazard.

OK, try this just to make sure that something is not obstructing the fuel inlet (needle and seat passage). Connect a short length of fuel hose to the carb fuel inlet nipple. Now try to blow through the hose using your mouth/lungs. With the carb top removed, you should be able to hear the air coming in through the needle/seat. If you can't hear air coming in like that, something is obstructing the fuel inlet or needle/seat area. If you can hear air entering the carb inlet, then you have either a defective fuel pump, or something is wrong with the marine tank/fuel lines. While you have the top off the carb, fill the bowl with gasoline before putting the top back on. When the top is back on, try to start it. If everything is satisfactory with the carb itself, you should get about 30 to 40 seconds run off the fuel in the bowl (your results may vary).

Ok , I have I believe to be a 2011 Craftsman riding mower with a 48 inch cutting deck and a 24hp Intek V-twin Briggs & Stratton engine that was given to me 3/25/18 of this year. Engine model #446677 0463 E1. Previous owner said engine started backfiring while mowing then died. Since I had done auto mechanic work for several years and the mower still looked almost new I accepted it. Got it home and charged up the battery and give it a whirl. The engine completed about 4 or 5 revolution’s and it backfired. So did a little research on this issue. Found out it could be several things. So I removed the flywheel and checked for a bent flywheel keyway. It was fine. Next I pulled the valve covers and what do you know. Sitting on the mower on the left side it had dropped the pushrod out of the lower exhaust tapper and sucked it into the engine. The valve guide and spring looked fine and were not stuck as I could compress the spring and valve without any hard spots. On the intake valve it had about .0012 clearance and the pushrod was barely hanging on. The right side of the engine was almost as bad finding both pushrods barely hanging on and not dropping out of the tappers. I have tried to use a telescoping magnet and run it inside the engine just to the right of where the pushrod sets on the lobe. I’m not sure if the pushrod is steel or aluminum? Anyway no luck from that point of entry. Next I removed the oil filler tube and went from that angle but the magnet only grabbed the crankshaft and wouldn’t allow me to move the magnet all around in the crankcase to retrieve the stray pushrod. It got dark on me so I had to stop for the night. Tomorrow I’m going to drain the oil and remove the drain valve and give it a try that way and after the oil is drained I had thought about jacking up the opposite side of the mower so that the pushrod might be loose in the crankcase and slide or roll to the side of the crankcase where the filler tube and oil drain valve are and maybe get lucky and be able to retrieve it. What I would like to know is the exhaust pushrod steel or aluminum and do you have any suggestions that wouldn’t require the engine to have to be torn down ! I sure could use a engine repair manual showing how to separate the engine case if needed to extract the rougue pushrod. Anything you can suggest or can me to download would be awesome. Thanks Tim F.

"Is the brake caliper hooked to the flywheel on this thing?" Yes it is. By means of the drive belt. The OP stated the the engine seems to run at slower RPM than before the heat treatment and that now executing turns has an effect on RPM/power, depending on which way you turn. I can only correlate that to something that would affect how much effort is required to move the machine across terrain. It IS NOT that the engine really makes more power during turns,m it is because the loading of the engine changes during turns (due to a sticking brake caliper). After I posted last night I also realized that it is entirely possible that this V-Twin Vanguard engine might only have 1 cylinder making good power. With only 1 cylinder putting out good power, the other cylinder constitutes an added load, thereby lowering RPM.......and making the engine run at full open throttle but never really reaching governed RPM. Hence the engine is able to speed up some when conditions occur that lessen the total loading.......or to "bog down" easier when loading increases. And a sticking brake caliper is capable of doing that. Vanguard twins can lose a cylinder entirely and the exhaust note will not sound much different, so it is not as apparent that you only have 1 good cylinder remaining. Heck, it's easier to detect an intermittent misfire than a completely absent cylinder on a Vanguard Twin just using the ears. This post was edited by mownie on Fri, Sep 13, 13 at 11:33